A 1986 study of the South Pole determined the cause of a hole in the ozone layer and led to an international treaty banning the production of chlorofluorocarbons (CFCs). Twenty years later, in an August 23, 2006, report, a scientist from the original expedition discusses the ozone’s slow recovery.

On May 28, 1959, in an experiment that would lead the way to manned space flight, the United States launched two monkeys to an altitude of 300 miles. A Voice of America news report details the travels of the two primates who survived the space flight and were the first in history to return safely to Earth.

On February 22, 1997, scientists in Scotland announce the creation of the world's first mammal to have been successfully cloned from an adult cell. Alan Colman, one of the scientists involved, describes the genetic makeup of Dolly the sheep, whose birth on July 5, 1996, had been kept a secret for almost eight months.

On March 11, 2011, an 8.9-magnitude earthquake struck the coast of Japan, rattling a 500-mile region and setting off a tsunami. A report from the U.S. Geological Survey describes the massive quake as one of the largest ever recorded.

In Hans Bay, big sharks mean big business and local cage divers grow uneasy with the crew's presence. The team continues to fight fatigue, and a mistake forces Brett to dive into shark-infested waters.

In the final hours of the biggest great white expedition ever attempted, a pod of killer whales and a streak of bad luck force Chris and the crew to take desperate measures to wrangle a shark in untested waters.